Wednesday, July 29, 1998 Published at 08:51 GMT 09:51 UKWorld: AmericasAnalysis: How the deal affects ClintonPresident Clinton has plenty to think aboutBy Gordon Corera of BBC Research

The deal giving Monica Lewinsky immunity from prosecution in return for "a full and truthful testimony" about her alleged affair with Bill Clinton is bad news for the president. But it does not mean he is in terminal trouble.

The scale of any damage to Mr Clinton's position will be determined by what Miss Lewinsky says when she testifies.

Reports say Miss Lewinsky will admit that she had sexual relations with the president - an allegation he has denied - but she will not say that the White House put pressure on her to lie about it.

If she testifies only about the alleged affair then the case could boil down to the president's word against hers. If such allegations were proven it would be embarrassing to Mr Clinton after his denial earlier this year, but would not mean he had broken the law.

The BBC Washington Correspondent, Stephen Sackur, says that if Miss Lewinsky does not testify about any alleged cover up, it could be a crucial blow to independent prosecutor Kenneth Starr.

An additional consideration for Mr Starr is the credibility of Miss Lewinsky because any change in her testimony would mean confessing to lying earlier when she signed a sworn affidavit saying she did not have sex with Mr Clinton.

The case for impeachment

Six months ago when Mr Starr started investigating allegations of sexual misconduct, he was not satisfied with a legal deal just based on Miss Lewinsky's testimony that she had sex with the president. He also wanted her to say that Bill Clinton and people close to him encouraged her to not tell the truth about that relationship.

If Miss Lewinsky does say that the president urged her to lie about the alleged affair while under oath - he denies these charges also - then the matter would become more serious for Mr Clinton. Congress might be moved to impeach the president for committing what the constitution describes as "high crimes and misdemeanours".

Only once in US history has a president been impeached - in 1868 Andrew Johnson fell foul of Congress, only for the Senate, who have the final say on the matter, to rescue him by a single vote.

Mr Clinton's legal team is already having a difficult time over a subpoena issued as part of Mr Starr's investigation. He is the first president to receive a Grand Jury subpoena to testify in a criminal investigation.

The president's lawyers are currently negotiating the timing and nature of any appearance before a Grand Jury. He would much rather not testify in any way, but refusing to give evidence and ignoring the subpoena would be a dangerous move - he would almost certainly be seen as having something to hide, and lose public support.

But if he does appear he would have to answer questions, under oath, on the evidence given by Miss Lewinsky.